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| United States Patent |
5,067,366
|
|
Gandiglio
|
November 26, 1991
|
Servo-assisted device for operating a vehicle parking brake
Abstract
A servo-assisted device for operating a parking brake of a moto vehicle is
described, consisting of a control lever for a brake cable or rod, mounted
rotatably on a pivot, a ratchet mechanism adapted to permit rotation of
the lever in a predetermined direction and a push button for disengaging
the ratchet mechanism; the principal characteristic of the invention
consists in the fact that the brake cable or rod is connected to the
control lever through an actuator pivoted beneath the control lever and to
a movable element of which the said brake cable is fixed.
| Inventors:
|
Gandiglio; Romolo (Villanova D'Asti, IT)
|
| Assignee:
|
Fiat Auto S.p.A. (Turin, IT)
|
| Appl. No.:
|
545715 |
| Filed:
|
June 29, 1990 |
Foreign Application Priority Data
| Jul 28, 1989[IT] | 67646 A/89 |
| Current U.S. Class: |
74/535; 74/538; 74/625; 188/106P; 188/156; 192/83 |
| Intern'l Class: |
G05G 005/06; F16D 065/14; F16D 019/00 |
| Field of Search: |
74/535,578,625,501.6
188/106 P,156
192/83
|
References Cited
U.S. Patent Documents
| 3620099 | Nov., 1971 | Stotz | 74/538.
|
| 3638766 | Feb., 1972 | Besoyan | 188/106.
|
| 4138905 | Feb., 1979 | Konishi | 74/535.
|
| 4629043 | Dec., 1986 | Matsuo et al. | 192/4.
|
| 4795002 | Jan., 1989 | Burgei et al. | 188/156.
|
| 4795003 | Jan., 1989 | Colgate | 192/83.
|
| 4819501 | Apr., 1989 | Kraus et al. | 74/535.
|
| 4854187 | Aug., 1989 | Walters | 74/535.
|
| 5001942 | Mar., 1991 | Boyer | 74/538.
|
| Foreign Patent Documents |
| 2815018 | Oct., 1979 | DE.
| |
| 3210402 | Sep., 1983 | DE.
| |
| 3238196 | Apr., 1984 | DE.
| |
| 3704018 | Aug., 1988 | DE.
| |
Primary Examiner: Herrmann; Allan D.
Assistant Examiner: Laub; David W.
Attorney, Agent or Firm: Shlesinger, Arkwright & Garvey
Claims
I claim:
1. A servo-system device for operating a vehicle parking brake, comprising:
a) a support bracket including a pivot;
b) a control lever rotatably secured to said pivot and operably associated
with one end of a tension wire of a vehicle parking brake for actuating
the tension wire;
c) a ratchet mechanism adapted to permit rotation of said control lever in
a predetermined direction;
d) means for disengaging the ratchet mechanism;
e) an actuator adapted to cause the tension wire to be tensioned
independently of said control lever;
f) said actuator being disposed between said control lever and the one end
of the tension wire such that said control lever, said actuator and the
tension wire form a chain in which said actuator is disposed mechanically
in series, thereby permitting said control lever to actuate the tension
wire independently of said actuator;
g) said actuator comprising an outer body pivotally connected to and
disposed underneath said control lever; and,
h) said actuator including a movable element carried by said outer body and
connected to the one end of the tension wire for actuating the tension
wire when said movable element is displaced.
2. A device according to claim 1, wherein:
a) said actuator is an electromechanical actuator; and,
b) an actuating switch disposed within a passenger compartment of the
vehicle for actuating said actuator.
3. A device as in claim 2, and further comprising:
a) an electronic central control unit adapted to cause actuation of said
electromechanical actuator in a predetermined manner such as to actuate
the parking brake.
4. A device as in claim 1, wherein:
a) said control lever includes a pulley secured to said pivot; and,
b) said puley engages the tension wire.
5. A device as in claim 1, wherein:
a) said ratchet mechanism includes a saw-toothed sector fixedly secured to
said support bracket;
b) a pawl cooperating with said saw-toothed sector and carried by said
control lever;
c) a push button carried by said control lever and connected to said pawl
for disengaging said pawl upon application of pressure on said push
button;
d) said saw-toothed sector including a terminal portion; and
e) an end stop element operably associated with said saw-toothed sector and
adapted to come into contact with said pawl immediately before said pawl
engages said terminal portion of said saw-toothed sector.
6. A device as in claim 5, wherein:
a) said end stop element is pivotally secured to said pivot;
b) a resilient biasing means adapted normally to maintain said end stop
element between said pawl and said terminal portion of said saw-toothed
sector; and,
c) said pawl being adapted, upon rotation of said control lever towards
said terminal portion of said saw-toothed sector, to displace said end
stop element against the action of said resilient biasing means for
engaging said terminal portion.
7. A device for operating a vehicle parking brake, comprising:
a) a support bracket including a pivot;
b) a control lever rotatably secured to said pivot and operably associated
with one end of a tension wire of a vehicle parking brake for manually
actuating the tension wire;
c) said control lever having a rest position wherein the tension wire is
substantially relaxed and the parking brake is disengaged, an actuated
position above said rest position wherein the tension wire is under
tension and the parking brake is engaged, and a disengaged position below
said rest position wherein the tension wire is substantially relaxed and
the parking brake is disengaged;
d) means for manually selectively positioning said control lever in one of
said rest, actuated and disengaged positions;
e) drive means for actuating the tension wire independently of said control
lever and while said control lever is in said rest position; and
f) said positioning means including means for permitting said control lever
to pivot past said rest position for manually relieving the tension wire
after said drive means has actuated the tension wire, thereby permitting
manual release of the parking brake if said drive means breaks down.
8. A device as in claim 7, wherein:
a) said drive means is disposed in series and between said control lever
and the one end of the tension wire such that the tension wire can be
activated independently by one of said control lever and said drive means.
9. A device as in claim 7, wherein:
a) said drive means is pivotally secured to said control lever.
10. A device as in claim 7, wherein:
a) said drive means is disposed below said control lever; and
b) said drive means includes a slidable element connected to the one end of
the tension wire thereby to actuate the tension wire when the slidable
element is displaced.
11. A device as in claim 7, wherein:
a) said positioning means includes a ratchet mechanism; and
b) said ratchet mechanism includes means for stopping said control lever at
said rest position.
12. A device as in claim 11, wherein:
a) said ratchet mechanism includes a saw-toothed sector fixedly secured to
said support bracket;
b) a movable pawl cooperating with said saw-toothed sector and carried by
said control lever;
c) means carried by said control lever for disengaging said pawl from said
saw-toothed sector; and,
d) means for stopping said control lever at said rest position.
13. A device as in claim 12, wherein:
a) said stopping means includes a member pivotable about said control lever
pivot;
b) said member includes an end portion engaging said pawl; and
c) a resilient biasing means for maintaining said end portion engaged
against said pawl at said rest position.
14. A device as in claim 13, wherein:
a) said saw-toothed sector includes an end portion disposed below said
member end portion; and
b) said biasing means is adapted to normally maintain said member end
portion above said sector end portion.
15. A device as in claim 14, wherein:
a) said pawl, upon rotation of said control lever towards said end portion
of saw-toothed sector, is adapted to displace said member end portion
against the action of said resilient biasing means for reaching and
engaging said saw-toothed sector end portion to relieve the tension wire
after said drive means has actuated the tension wire, thereby permitting
manual release of the parking brake.
16. A device as in claim 7, wherein:
a) said control lever includes a pulley secured to said support bracket
pivot; and,
b) said pulley engages the tension wire.
17. A device as in claim 7, wherein:
b) said drive means includes an actuating switch disposed within a
passenger compartment of the vehicle.
18. A device as in claim 7, and further comprising:
a) an electronic central control unit adapted to cause actuation of said
drive means in a predetermined manner.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a servo-assisted device for operating a
vehicle parking brake, adapted to permit the engagement/disengagement of
the parking brake without requiring any physical force on the part of the
user.
It is known that the device for operating the parking brake of a vehicle
currently consists of a lever pivoted to a bracket fixed to the floor of
the vehicle and connected to a brake cable the tensioning of which
controls the clamping of the rear brake shoes; in order to maintain the
operating lever in the desired position it is connected to a ratchet
mechanism which can be disengaged by means of a push button carried by the
hand brake lever itself; to engage the parking brake the user must grip
and pull the control lever upwardly by hand in such a way as to put the
brake cable under tension and, overcoming the resistance offered by the
brake shoes, consequently clamp these latter against the brake drum; once
positioned the brake lever holds the brake cable under tension (and
therefore maintains the parking brake engaged) in that the ratchet
mechanism stops it from returning to the rest position flush with the
vehicle floor; by disengaging the ratchet mechanism the lever is released
and can be returned to the rest position releasing the parking brake. The
described operations require that the user exert on the lever a distinct
physical force, in particular upon disengaging the ratchet mechanism in
that, in order to be able to actuate the release push button it is
necessary to pull the lever further.
SUMMARY OF THE INVENTION
The object of the invention is that of providing a servo-assisted device
for operating the parking brake of a vehicle, which can be operated by the
user without any physical force, in particular by means of the pressure of
a simple push button or switch, maintaining, however, the possibility of
operating the parking brake manually, for example in the case of breakdown
of the servo control.
The said object is achieved by the invention, which relates to a
servo-assisted device for operating a parking brake of a vehicle,
comprising a control lever for a brake cable or rod, mounted rotatably on
a pivot, a ratchet mechanism adapted to permit the rotation of the lever
in a predetermined direction, and ratchet mechanism disengagement means,
characterised by the fact that it further includes an actuator adapted to
cause tensioning of the said brake cable or rod, the said brake cable or
rod being mechanically connected to the control lever through the said
actuator.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention there is now given a
non-limitative description of an embodiment, with reference to the
attached drawings, in which:
FIG. 1 schematically illustrates a vehicle provided with a parking brake
operating device formed according to the invention;
FIGS. 2, 3 and 4 illustrate respective side views of the control device
according to the invention in different operating positions; and
FIG. 5 schematically illustrates the operation of the device of FIGS. 2, 3
and 4.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the said Figures, the reference numeral 1 indicates a
known vehicle, in this case a motor vehicle, a passenger compartment 2 of
which, delimited at the bottom by a floor 3, houses a servo-assisted
device 4 for operating a parking brake 5 of the vehicle 1 which, according
to a known configuration makes use of the rear brakes of the vehicle 1 and
comprises respective brake shoes 6 (or brake pads in the case of disc
brakes) adapted to cooperate frictionally with a drum (disc) 8 of each
rear wheel 9 of the vehicle 1 upon tensioning of a known brake cable or
pull rod 10 connected in a known way not illustrated for simplicity to the
brake shoes 6, tensioning of which is effected, as will be described, by
means of the control device 4.
The device 4 includes an operating lever 12 adapted to actuate the brake
cable 10 and disposed adjacent the floor within a seat 13 formed through
the floor 3; the lever 12 is pivoted to the floor 3 in that it is
rotatably mounted on a pivot 14 in turn supported by a bracket 15 fixedly
secured to the floor 3 within the seat 13; the brake operating device 4
further includes a ratchet mechanism 16 adapted to permit the rotation of
the lever 12 in only one predetermined direction, indicated by the arrow
in FIG. 3, such as to move it away from the floor 3, and ratchet mechanism
disengagement means 16 defined by a push button 18 projecting axially from
a handle 19 of the lever 12. In particular, the ratchet mechanism 16
comprises a saw toothed sector 20 formed fixedly with the support bracket
15 of the pivot 14 coaxially with this latter, and a pawl 22 rockably
carried and projecting laterally from the lever 12, preferably against the
action of resilient means of known type not illustrated for simplicity,
snap-engaging with the toothed sector 20 in a manner such as to slide over
the teeth of this latter when the pawl 22 is displaced, together with the
lever 12, in the said predetermined direction and to engage against the
tooth with which it is at that moment in contact when the lever 12 is
stressed to turn in the opposite direction, in this example towards the
floor 3, in such a way as to prevent this rotation as long as the pawl 22
has not been disengaged from the toothed sector 20; this disengagement is
effected in a known way by pressing the push button 18 which is connected
in a known way to the pawl 22 by means, for example, of a push rod 24
housed longitudinally within the interior of the lever 12, which push rod
causes, following pressure on the push button 18, rotation of the pawl 22
in the direction of the arrow (FIG. 4) with consequent disengagement
thereof from the toothed sector 20.
According to the invention the device 4 further includes an
electromechanical actuator 30 connected to the brake cable 10 and acting
to cause tensioning of this latter without any necessity of manual
intervention on the part of the user whilst leaving available the
possibility of causing tensioning of the cable 10 in the traditional
manner, by means of the upward rotation of the lever 12; according to the
principal characteristic of the invention, in fact, the brake cable 10 is
mechanically connected to the control lever 12 through the actuator 30
itself, which is mechanically disposed in series with the kinematic chain
constituted by the lever 12 and the cable 10. In particular the actuator
30 comprises a body 31 housing the mechanism and which is pivotally
suspended to the control lever 12 beneath this, an electric motor 32
projecting axially from the body 31 parallel to the lever 12, and a
movable element 34 supported by the body 31 and fixedly secured to the end
36 of the cable 10 opposite the brake shoes 6; in this example the body 31
is rockably pivoted to an ear 35 formed integrally on the underside of the
lever 12, and the movable element 34 is defined by a cylindrical stem
which slides rearwardly actuated by the motor 32 parallel to the motor 32
itself, in such a way as to tension or release the cable 10 respectively
when the element 34 is displaced in the direction of the arrow (FIG. 4) or
in the opposite direction.
Within the lever 12 coaxially with the pivot 14 is arranged a pulley or
drum 38 over which the brake cable 10 is partially wound, biased so as to
favour its movement by the actuator 30; according to a further
characteristic of the invention, fixed to the toothed sector 20 there is
arranged an end stop element 40 adapted to determine the rest position of
the lever 12 with the pawl 22 immediately before this latter reaches,
during descending movement of the lever 12 towards the floor 3, a terminal
section 42 of the toothed sector 20; in particular the end stop element 40
is movable to permit the release of the brake in the case of a loss of
current or breakage of the motor 32. The element 40 is in fact defined by
a bracket freely mounted coaxially with the pin 14 and which, therefore,
is fixed to the toothed sector 20 only in the sense that it is carried by
an element (the pin 14) in turn supported by the same element (the bracket
15), which also carries the toothed sector 20. The end stop element or
bracket 40 is moreover biased, by means of a radial arm 41, by associated
resilient means defined by a coil spring 43 acting normally to maintain
the end stop element 40 between the pawl 22 and the end section 42 of the
toothed sector 20, as well as to oppose with its resilient reaction the
rotation of the bracket 40 on the pin 14 in the direction the arrow (FIG.
4). The pawl 22 is further shaped and positioned in such a way as to be
able, following rotation of the lever 12 towards the toothed terminal
section 42, to displace the end stop element 40, making it turn in the
direction indicated in FIG. 4 against the action of the said resilient
means 43 in such a way as to render accessible the section 42 of the
toothed sector 20; in this way the pawl 22 is able to reach and,
subsequently, engage (upon release of the push button 18) the terminal
section 42 itself.
The actuator 30 is controlled by an actuation switch 46 (FIG. 1) disposed
within the passenger compartment 2 of the vehicle 1 in a position easily
accessible to the user when driving the vehicle itself, for example on the
dashboard; this switch 46, for example of the push button type, directs
current to the motor 32, which is of reversible type, in such a way as to
make it turn in the desired direction; preferably, furthermore, the
actuator 30 is also controlled by a central electronic control unit 48,
for example of the known microprocessor type, wired in such a way as to
give priority to the control of the actuator 30 when the vehicle 1 is in
operation and programmed in such a way as to be adapted to cause the
parking brake 5 of a vehicle 1 to operate, causing the operation of the
actuator 30 in a suitable direction upon reversal of the vehicle 1 if it
takes place in predetermined conditions, for example if the reverse gear
is not engaged.
The operation of the device described is shown in FIG. 5; when the lever 12
is in the position illustrated in FIG. 2, which is the rest position, and
the push button 46 is not actuated, the parking brake 5 is in the
configuration indicated in FIG. 5(a); the movable element 34 is at the end
of its stroke towards the drum 38 and the cable or pull rod 10 is not
tensioned; consequently the brake shoes 6, under the effect of their own
biasing means (known and not illustrated for simplicity) are spaced from
the drum 8 and the vehicle 1 is not braked; if the user wishes to actuate
the parking brake 5 and, therefore, presses the push button 46, or if a
predetermined condition for the intervention of the central control unit
48 occurs, the actuator 30 is energised and the configuration of FIG. 5(b)
obtains: the motor 32 displaces the rod 34 in the direction of the arrow
towards the ear 35 causing tensioning of the brake cable 10 which passes
over the drum 38 actuating the brake shoes 6 of each wheel 9 bringing them
into contact with their associated brake drums with consequent braking of
the vehicle 1, all without it being necessary to move the lever 12 and,
therefore, without the user having to exert any physical force to
disengage the parking brake 5 it will be necessary to press the push
button 46 again (or else the central control unit 48 will again intervene
upon the termination of the conditions which have caused the preceding
intervention) to energise the actuator 30 in such a way as to cause the
motor 32 to rotate in a direction opposite the preceding direction; in
this way the rod 34 is made to translate towards the drum 38 and the brake
cable 10 is consequently released permitting the brake shoes 6 to become
spaced from the respective brake drum 8 so that the configuration in FIG.
5(a) is regained.
If the actuator 30 should break down with the parking brake engaged, or
rather when configuration in FIG. 5(b) obtains, it is possible, according
to the invention, manually to disengage the brake 5 when it is necessary
to cause the vehicle 1 to move; for this purpose it will be necessary
(FIG. 4) to cause the lever 12 to rotate manually in the direction of the
arrow, first having pressed the push button 18 in such a way as to
disengage the pawl 22 from the toothed sector 20; the lever 12 will now
pass from the rest position (indicated in broken outline) to the position
illustrated in FIG. 4 in that the end stop element 40 which cooperates
with the pawl 22 is pressed by this latter to rotate against the action of
the spring 43 in the direction of the arrow; this rotation of the lever 12
causes a slackening of the brake cable and, upon release of the push
button 18, the locking of the lever 12 in the position now assumed, in
that the pawl 22 is carried into correspondence with the section 42 which
it engages as soon as the push button 18 is released; in this condition
the configuration indicated in FIG. 5(c) obtains in that the lever 12 is
displaced beneath the rest position, the brake cable 10 is partially
slackened and the brake shoes 16 are spaced from the respective brake drum
8 by a distance sufficient to allow the vehicle 1 to move.
If the actuator 30 becomes unserviceable when the parking brake is not
operated, or in any case in which the user prefers manually to operate it,
it is possible to operate in a conventional manner as if the actuator 30
were not present; in fact (FIG. 3) it will be sufficient to pull the lever
12 in such a way as to cause it to rotate in the direction of the arrow to
make it pass from the rest position to that illustrated; during this
movement the pawl 22 slides over the teeth of the sector 20 successively
engaging them and the brake cable 10 is tensioned in that the raising of
the lever 12 also causes the raising of the actuator 30 suspended from it
and to which the cable 10 is anchored; upon reaching the desired position
the pawl 22, engaging against the sector 20, prevents the reverse rotation
of the lever 12 until it is released with the push button 18; during the
return stroke, or rather with the pawl 22 disengaged, the rest position is
identified to the user by the fact that the pawl 22 strikes against the
end stop element 42, which is only movable against the action of the
spring 43, that is only by exercising on it a force greater than the
resilient reaction exerted by the spring 43 itself; therefore, when the
rest position of the lever 12 is reached it stops (the cable 10 in the
meantime being completely slackened) and, upon tending to continue the
movement the user will notice a resistance to rotation which just
indicates that the end of stroke position has been reached. If this is
inadvertently exceeded, as the user ceases to press on the lever 12 the
resilient reaction on the spring 43 will automatically return the lever 12
into the rest position, which is the equilibrium position.
From what has been described the advantages connected with the invention
are evident; thanks to the particular assembly of the actuator 30 the
normal parking brake operating lever 12 is still operative but, however,
the parking brake can also be engaged simply by acting on an electrical
switch; the possible subjection to an electronic central control unit
further permits automatic engagement of the parking brake in particular
conditions, for example if the vehicle 1 has to stop and, then, start off
again and, likewise automatically, to exclude it when it is no longer
necessary. Finally the device 4 is perfectly operable if the actuator 30
should break down.
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